The DS2119M Ultra3 LVD/SE SCSI terminator is both a low-voltage differential (LVD) and single-ended (SE) terminator. The multimode operation enables the designer to implement LVD in current products while allowing the end-user SE-backward compatibility with legacy devices. If the device is connected in an LVD-only bus, the DS2119M will use LVD termination. If any SE devices are connected to the bus, the DS2119M will use SE termination. This is accomplished automatically inside the part by sensing the voltage on the SCSI bus DIFFSENS line.
For the LVD termination, the DS2119M integrates two current sources with nine precision resistor strings. For the SE termination, one regulator and nine precision 110Ω resistors are used. Three DS2119M terminators are needed for a wide SCSI bus.